question_answer 18)

  The binding energy of a H-atom, considering an electron moving around a fixed nuclei (proton), is (m = electron mass). If one decides to work in a frame of reference where the electron is at rest, the proton  would be moving around it By similar arguments, the binding energy would be This last expression is not correct because (a) n would not be integral (b )Bohr-quantisation applies only to electron (c) the frame in which the electron is at rest is not inertial (d) the motion of the proton would not be in circlar orbits, even approximately

Answer:

  In a hydrogen atom, electron revolving around a fixed proton nucleus has some centripetal acceleration. Therefore, its frame of reference is non inertial. In the frame of reference, where the electron is at rest, the given expression cannot be true for binding energy as the frame in which electron is at rest would not be inertial. Choice (c) is correct.